**4. Conclusions**

It can be concluded that the lees of sparkling wines elaborated using the traditional method have a real capacity to release proteins and polysaccharides. However, the proportion of polysaccharides and proteins from lees autolysis is very low in the young sparkling wines, roughly only 2–3% in the first year of ageing and around 7% in the third. This suggests that the real impact of polysaccharides and proteins from lees autolysis in the sparkling wines disgorged before the end of the first year should be very low. Wine producers should bear this conclusion in mind since most sparkling wines elaborated by the traditional method are aged for less than 1 year and those made by other methods are aged even less. Consequently, only sparkling wines aged for longer would therefore benefit from a greater presence of polysaccharides and proteins from yeast autolysis.

It can also be stated that lees consume oxygen and therefore they protect sparkling wine against oxidation. However, the lees' capacity to consume oxygen decreases

drastically after 3 years of aging, reaching values lower than those of the theoretical oxygen permeability of the crown cap after about 3 years and a half of aging. Producers of sparkling wines should also bear in mind because after this time the ability of the lees to protect against could not be enough. Some panelists considered that the quality of the sparkling wines was negatively affected after 5 years of aging due to excess oxidation. These data explain what AOC Cava winemakers know empirically. Only some high-quality sparkling wines made using the traditional method can age more than 3 years without being affected by oxidation, and in this case, sparkling wines reach an extraordinary level of complexity that only long aging can provide.
